Kratom strains are naturally bitter. Brewing the tea for more than two minutes will further result in a bitter flavor. Make sure to choose your strain and brew time as per your taste.
If you find the tea to be too strong, you may choose to add sugar, stevia, or honey for a sweet taste or dilute it with some more water.
Do not use kratom extracts as its constituents are easily broken down and lost in hot water. Additionally, it is heavy on the pocket!